Cell Biology; Biological Membranes

HideShow resource information
  • Created by: KayshaN
  • Created on: 09-10-19 17:07
Outline 4 Functions of Biological Membranes.
1) compartmentalisation of cell 2) organisations and localisation in cell 3) transport in and out cell 4) detection and transmission of signals
1 of 41
What did Overton (1890) say about the Cell Membrane?
He said the cell surround by selectively permeable barrier and he could learn about the structure from what the barrier let across. Lipid soluble subs crossed, concluded contained lipids
2 of 41
What did Gorter and Grendel (1925) do?
followed up Langmeir trough, took number RBCs and extracted lipids, took lipid/solvent mix and compressed, measure SA deduced x2 SA RBCs, must be bilayer
3 of 41
Why is Selectivty a problem with Gorter and Grendels model?
Selectivity- glucose readily in to cell but similar galactose isnt, where is this selected for? transport of ions, must be something else.
4 of 41
What did Davson and Danielli (1935)propose about the lipid bilayer from the concept of enzyme-substrate specificty?
They proposed the sandwich model, where on the surface of both sides of the lipid bilayer coating of proteins. Where enzymes can bind to specific proteins
5 of 41
Singer and Nicolson (1973) proposed what?
The fluid mosaic model, proteins not uniform, some through the entirety of the mem.
6 of 41
Membrane Topology: two types?
Cytoplasmic Side (in contact cytoplam), Exoplasmic Side
7 of 41
Name the 4 Phospholpids
Phosphatidylcholine, Phosphatidylserine, Phosphatidylethanolamine, Sphingomyelin
8 of 41
Phosphatidylcholine: which side of the ER membrane is it synthesised on?
Cytoplasmic Side, inserted into this side.
9 of 41
Outline Role of Scramblases.
phospholipid translocaters, PL on added to cytoplasmic side so these tranfer them to other side so equal growth. Not head specific.
10 of 41
Membrane Asymmetry: Which phospholipids should be on the Exoplasmic side?
Phosphatidlycholine and Sphingomyelin
11 of 41
Membrane Asymmetry: Which phopsholipids should be on the Cytoplasmic side?
Phosphatidlyserine and Phosphatidlyethanolaine
12 of 41
Outline Role of Flippases.
head group specific, transfer PS and PE from exoplasmic to cytoplasmic
13 of 41
How do mitrochondria get phospholipids?
Cant syn own so use phospholipid exchange proteins, take out ER membrane then insert into mitrochondira membrane.
14 of 41
Outline some roles of Glycolipids.
cell-cell recognition, immune response, blood types, always found exoplasmic side
15 of 41
Outline basic role Cholesterol.
Steroid, inflexible, stabilises bilayer
16 of 41
What are the three types of membrane proteins?
peripheral membrane proteins, integral membrane proteins, lipid anchored membrane proteins
17 of 41
Define integral membrane proteins.
inserted into the bilayer, most one side to the other
18 of 41
Outline the three types of integral membrane proteins?
single membrane spanning domain, multitransmembrane domain protien, beta sheet barrel structure, one side membrane physically inserted
19 of 41
Define peripheral membrane proteins.
membrane protiens that are associated with the bilayer through protein-protein interactions but not inserted
20 of 41
What are the two most common peripheral membrane proteins?
myristyl anchor and femesyl anchor
21 of 41
Outline the FAAP Experiment.
1) take cell and label all lipids on surface with dye 2) laser, bleach certain area 3) this destroys flourescence 4) after 20 minutes there is a recovery of flourescence
22 of 41
What can be concluded from the FAAP experiment?
neighboring lipids moved by lateral diffusion
23 of 41
How can lipids move other than lateral diffusion?
flextion, rotation and flip-flop- need lots of energy so rare without enzymes
24 of 41
Define 3 reasons why it is important for the membrane to be fluid?
1) allow membrane fuse with others, e.g. vesicle transport 2) membrane shared equally with daughter cells 3) cell migration e.g. macrophages
25 of 41
What is the big problem with the memrbane being fluid?
Phase Transistion- changes state over a narrow temperatyre range, cooler= rigid immobile, heat= liquid, disordered
26 of 41
What does increasing chain length of fatty acid chains do to the membrane overall?
increases the melting point
27 of 41
Decribe the effect of double bonds in the fatty acids.
Introduce kinks into tails, the more they have the more kinks. Means that the phospholpids further apart which decreases Van Der Waals forces.
28 of 41
How do prokarayotes maintain membrane stability?
Temp increase->Make fatty acids with decreased chain lengths (less VDW) and with increases double bonds.
29 of 41
What is Cholestrol?
ampithatic, steroid ring structure, rigid, prevents phase transition
30 of 41
What effect does Cholestrol have on the membrane?
37+ makes membrane less fluid by stabilising interactions, lower temps= prevents phopspholipids from interacting each other
31 of 41
What are channel proteins?
pores through membrane, made beta sheets, most non directional, some selectivity, driven by concentration gradient
32 of 41
Channel proteins are not always open, what are the four types of gates?
Voltage Gated-charge, Ligand gated (Extra)- regulated by other proteins/molecules outside, Ligand- Gated (Intra), Mechanically gated- physcial process, chage shape
33 of 41
What are carrier protiens?
required for transport almost all small organic molecules, highly selective, slow transport, passive or active
34 of 41
Outline Glut1 as a example of a carrier protein.
Glucose binds to the site, shifts to alternative conformation, released into cell, return to original conformation
35 of 41
Define Electrochemical Gradient.
e.g. membrane potential negative inside and postive outside, move in
36 of 41
Outline three types of pumps (carrier protiens)?
Coupled transporters, ATP driven transporters, light driven pumps
37 of 41
Outline the Sodium-Potassium Pump.
Energy from ATP hydrolysis is used to chnage shape carrier, 3 NA out against conc gradient, 2 K into cell
38 of 41
How is glucose brought into the gut agaisnt concentration gradient?
Coupled transport with sodium potassium pump, Na diffuses into cell and glucose with it
39 of 41
What are the two types of Coupled Transport?
Symport=movement same direction, Antiport= movement different direction
40 of 41
Outline the effect of Digoxin.
Drug treat heart faliure, inhibits sodium potassium pump, less concentration graient of NA, lessens coupled transport of NA/CA in muscles, less Ca out, higher interceullular, higher contractions, heart beating
41 of 41

Other cards in this set

Card 2

Front

What did Overton (1890) say about the Cell Membrane?

Back

He said the cell surround by selectively permeable barrier and he could learn about the structure from what the barrier let across. Lipid soluble subs crossed, concluded contained lipids

Card 3

Front

What did Gorter and Grendel (1925) do?

Back

Preview of the front of card 3

Card 4

Front

Why is Selectivty a problem with Gorter and Grendels model?

Back

Preview of the front of card 4

Card 5

Front

What did Davson and Danielli (1935)propose about the lipid bilayer from the concept of enzyme-substrate specificty?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Human Biology resources:

See all Human Biology resources »See all Biological Membranes resources »